Welding consumables include flux products, welding wire or electrodes, and other materials that are consumed during a welding process. In the manufacture and use of such welding consumables, it is sometimes desirable to measure and control the moisture, carbon dioxide (CO2) content, or content of other material such as nitrogen (N), etc., of the consumable, as well as the propensity of the consumable to absorb or release moisture or other elements or materials (e.g., N, CO2), since these characteristics may affect the welding process and the ultimate weld joint created thereby. Furthermore, the amount of moisture absorbed by welding flux and electrodes is important, as moisture on or in either can lead to substandard weld properties. It is thus desirable for welding consumable suppliers to characterize the moisture content (and CO2 content) and absorption rates for these products, for both the design and development of new products and for quality control purposes during manufacturing. The moisture transfer characteristics can be determined by weight measurements before and after exposure of a welding consumable to a humid (or arid) environment.
In order to adequately characterize the absorption tendencies, conventional practice has been to initially weigh a sample and to thereafter place the sample in an environmental chamber with controlled temperature and humidity. After exposure to the controlled atmospheric conditions for a certain amount of time, the test sample is removed from the chamber and again weighed, where the change in weight is indicative of the amount of moisture gained (or lost), and the weight change and the exposure time can be correlated to estimate an absorption rate.
As the moisture absorption transfer characteristics of welding consumables (and/or raw materials used in the production thereof) is a function of time, it is generally desirable to measure the transfer effects at a number of different times. For instance, testing positive moisture absorption (gain) at a given set of chamber humidity and temperature conditions may be done for an extended time period, such as 24 hours. In order to obtain a spread in the measured data, exposure times of 0, 1, 2, 4, 6, 8, 10, 12, 18, and 24 hours may be selected, where ten samples are initially measured and placed in the environmental test chamber. After one hour of humidity exposure, the chamber door is opened and one sample is removed and weighed to obtain a first data point. A second sample is removed an hour later and weighed, and this process continues with samples being removed and weighed at 4, 6, 8, 10, 12, 18, and 24 hours to complete the test. While this approach obtains a 24 hour spread of data in a single day of testing, test personnel must be present at each selected time period to remove and weigh a sample. Furthermore, the humidity exposure environment is disturbed by opening and closing the chamber door every time a sample is removed for weighing. Also, the samples may lose a significant amount of acquired moisture while being transported from the environmental chamber to the weighing station. Alternatively, a first sample could be tested alone for 1 hour, with a second sample being tested alone for 2 hours, and so on, with the final sample being tested alone for 24 hours. This approach may advantageously provide for undisturbed exposure of the tested samples throughout the entire test until removal for weighing. However, the test chamber is occupied for over 80 hours, and requires test personnel to be present to start a new test as each prior test is completed. Choosing between these conventional methods is thus a tradeoff between obtaining erroneous data because of atmospheric disturbance when removing a sample from the environmental chamber and increased testing cost by occupying the chamber for long periods of time. Moreover, in each approach, a consumable product sample is needed for each data point, and the interim moisture transfer behavior between test points is not measured. Furthermore, the addition of more test points necessitates usage of more samples and either further intermediate disturbance or longer allocation of test chamber resources. Thus, there is a need for improved methods and measurement systems for determining transfer characteristics of welding consumables.